Kingmambo, whose arthritic condition in his lower neck caused him to miss a key portion of the breeding season, is back covering mares at William S. Farish's Lane's End Farm near Versailles, Ky."He successfully bred mares the last four days," Farish said April 18. "The vets are pleased with his progress. He keeps getting stronger and more comfortable very day. Right now, we're just sending one mare a day to him."Kingmambo, a 15-year-old son of Mr. Prospector out of the champion Nureyev mare Miesque, first was relieved of stallion duty in late February because of a leg injury. He later was diagnosed with an arthritic condition in his lower neck that precluded him from breeding. Kingmambo, who has sired 54 stakes winners, stands for $300,000.